With the above standard command all voices are played together. To practice something it is sometimes nice to have only your own voice alone, you can do this by quieting/muting all voices except your own. The voices to be muted are listed after the option -Q separated by comma. The value 0 means all voices, the number of the other voices is given by their order in the output. So in the file I have, Soprano would be 1, Alto 2 and the men’s voices 3. Including the number mutes the voice, including it with a minus sign plays it. So let’s say I want to practice the alto voice, I’ll mute all but voice 2:

timidity -Q 0,-2 Was-soll-das-bedeuten.midi

It’s also simple to transpose stuff, this will play the song two semitones higher: